1. Field of Invention
The present invention relates to a complementary thin film transistor circuit (hereinafter, referred to as a CMOS circuit) including thin film transistors (TFTs). More particularly, the present invention relates to a complementary thin film transistor circuit including thin film transistors using a substantially monocrystalline semiconductor film made by performing laser irradiation on a semiconductor film, an electro-optical device using the same, and an electronic apparatus.
2. Description of Related Art
As a method to fabricate a thin film transistor on a general purpose glass substrate at a low temperature, a related art method is disclosed in which a hole is punched in an insulating film on a substrate, an amorphous silicon film is formed on this insulating film and in the hole, and thereafter laser light is irradiated on the amorphous silicon film, while maintaining an unmelted amorphous silicon in the bottom portion of the hole and a melted amorphous silicon film in the other portions, in order to generate a crystal growth using the amorphous silicon that is maintained in the unmelted state as a crystal nucleus, thereby providing a region centered on the hole in a surface of the amorphous silicon film as a substantially monocrystalline silicon film, as described in “Single Crystal Thin Film Transistors” (IBM Technical Disclosure Bulletin August 1993 pp257–258) and “Advanced Excimer-Laser Crystallization Techniques of Si Thin-Film For Location Control of Large Grain on Glass” (R. Ishihara et al., proc. SPIE 2001, vol. 4295, p14–23.) described below.
Because this substantially monocrystalline semiconductor film has no crystal grain boundaries or less crystal grain boundaries, when carriers, such as electrons or holes flow, a barrier is significantly reduced as compared to a polycrystalline semiconductor film.
By constructing a semiconductor device using this substantially monocrystalline semiconductor film in the semiconductor thin film, an off-current suppressing effect or mobility thereof is excellent, thereby being capable of easily realizing a thin film transistor that is compatible with a high-speed operation.
When a CMOS circuit including the thin film transistor formed using this substantially monocrystalline thin film is constructed, two contacts are required for leading out an output electrode from each of the two thin film transistors constituting the CMOS circuit. However, the spacing between the transistors tends to be reduced and the thin film transistors used in a driver circuit or the like also tend to become small as a result of the recent trends towards miniaturization of electronic devices. This is also the case in the CMOS circuits. In this case, because the output contact region becomes narrow, this prevents the realization of good contacts, which in turn causes a problem of hindering miniaturization. Further, in case of not attempting miniaturization, good contacts in which the output contact region becomes narrow may not be obtained depending on constructions.